This invention relates generally to fastener-driving tools having magazine systems for storing and delivering strips of attached fasteners to a nosepiece where a reciprocating driver blade drives individual fasteners into a workpiece, and more specifically to a magazine rail system for such a tool.
Fastener-driving tools, which may be pneumatically-powered, combustion-powered or powder activated, are widely used for driving fasteners of a type having an elongate shank with a pointed end and a head. Typically, such fasteners are designed to be forcibly driven through a workpiece into a substrate. Such fasteners include nails designed to be forcibly driven into wood and drive pins designed to be forcibly driven into concrete or masonry. Typically, in such drive pins, the shank has a portion flaring outwardly where the shank adjoins the head. An exemplary use of such drive pins is for attaching metal channels, which are used to mount plasterboard walls, or other metal workpieces to concrete substrates.
Many fastener-driving tools require such fasteners to be fed in strips, in which the fasteners are collated, through magazines having mechanisms for feeding the strips of collated fasteners. Commonly, such fasteners are collated via carriers molded from polymeric materials, such as polypropylene, with individual sleeves, bushings, or holders for the respective fasteners, and with frangible bridges between successive sleeves, bushings or holders. Examples of such fasteners collated via such carriers are disclosed in Haytayan U.S. Pat. Nos. 3,927,459; 3,954,176 and 4,106,618; in Whitledge U.S. Pat. No. 4,718,551 and in Steffen et al. U.S. Pat. No. 4,932,821.
U.S. Pat. No. 5,069,340 to Ernst et al., which is incorporated by reference, discloses a strip of fasteners for use with a fastener-driving tool. The strip of fasteners featuring a molded carrier configured so that each fastener is held within a generally cylindrical sleeve. Each sleeve has opposed windows configured to receive corresponding opposed ribs of a fastener-guiding device. Each window is bordered by radially extending upper and lower portions defining a guide channel. Frangible bridges secure adjacent carriers, and their corresponding fasteners, to each other.
One operational condition experienced with prior art fastener strips is that in some cases, strips become misaligned in the magazine. In other words, the fasteners are oriented at an angle other than 90xc2x0 relative to the workpiece, assuming 90xc2x0 orientation of the tool. Explained differently, the fastener is oriented in a non-parallel orientation relative to the driver blade prior to driving. If a misaligned strip delivers a misaligned fastener to the nosepiece for impact by the driving blade, the fastener may be improperly driven and/or bend into rigid substrates, causing a bent or xe2x80x9cfishhookxe2x80x9d configuration which requires driving of an additional fastener into the workpiece. Obviously, this practice is wasteful of time and materials, and in some cases may spoil the workpiece.
Another operational condition of fastener-driving tools using magazine-fed fastener strips is that in some cases the strips become caught or stuck in the magazine at the rear end of the tool opposite the nosepiece end. One explanation for this stuck condition is that the strips are molded of polymeric material such as polypropylene or equivalent material, the dimensions of which are inherently difficult to control or to maintain within strict tolerances. Especially when the fastener strips are guided solely by rails engaging the opposing strip windows as described above, it may be difficult for the operator to efficiently insert strips and obtain optimum alignment. Thus, the magazine loading operation may become unduly time consuming and potentially frustrating to the operator.
One attempted solution to this problem is that the magazine may be constructed with rails which engage only bottom surfaces of the fastener-holding strip sleeves. While this alternative promotes easy loading, it does not maintain the proper alignment of fasteners just prior to their being driven by the driver blade. Thus, misaligned or xe2x80x9cfish hookedxe2x80x9d fasteners may result from this arrangement.
Another disadvantage of a magazine configured to engage the lower ends of the fastener holding strip sleeves is that when the tool is operated in an inverted position, such as when operators operate the tool for driving fasteners overhead, the fasteners become vertically misaligned in the magazine and cannot be properly engaged by the driver blade.
Accordingly, a first object of the present invention is to provide an improved fastener-driving tool magazine which facilitates easy loading of fastener strips.
Another object of the present invention is to provide an improved fastener-driving tool magazine which enhances fastener alignment relative to the driver blade.
Yet another object of the present invention is to provide an improved fastener-driving tool which facilitates alignment of the fastener strip when the tool is used in a variety of positions, including inverted.
The above-listed objects are met or exceeded by the present magazine rail system, which features a dual portion guidance system for collated fastener strips. A first portion of the magazine is configured for easy loading of fastener strips and engages the strips at lower ends of the sleeves. At a designated portion of the magazine, a second portion of the guidance system engages the fastener strip in the window portion of each sleeve for facilitating proper alignment prior to engagement with the driver blade.
More specifically, the present invention provides, in a fastener-driving tool having a reciprocating driver blade for driving fasteners into a workpiece, a magazine configured for storing and feeding at least one collated strip of fasteners to the driver blade, including a housing defining a feed end, a driving end and a guidance portion disposed between and contacting the two ends. The guidance portion has at least two guidance formations, a first guidance formation configured for engaging the fastener strip at a first location, and a second guidance formation configured for engaging the fastener strip at a second location.
Each fastener strip includes a plurality of sleeves having a lower edge and a window channel defined by at least one and preferably two opposing radially projecting portions, and the first guidance formation is configured for engaging the strip at the lower edge, and the second guidance formation is configured for engaging the strip in the window channel. Preferably, the fastener strip is supported only by the first guidance formation in a first zone of the magazine, and only by the second guidance formation is a second zone of the magazine.
In another embodiment, a fastener driving tool has a magazine including a housing having a first guidance formation and a second guidance formation, the first guidance formation configured for guiding a fastener strip in a first location, the second guidance formation configured for guiding the fastener strip in a second location, the first location being different from the second location. In the preferred embodiment, the housing is configured so that the fastener strip is guided first only by the first guidance formation, then only by the second guidance formation.